It has long been the practice in the construction of wheels for trucks and other heavy duty highway or off-highway equipment, including military vehicles, to provide a multi-piece type wheel assembly utilizing a rim of the split-type in order to facilitate the mounting or demounting of heavy duty tubeless pneumatic tires thereon. In such multi-piece wheels, it has also been conventional to employ a sealing member, such as an O-ring or other sealing ring having specially contoured cross-sectional configurations, which is interposed between the removable flange ring and the other disc and rim parts of the wheel to seal the tire and rim to maintain the necessary air tightness between them. Typically a groove is required for inserting the sealing member and retaining the same in place, which in turn has heretofore required shaping of such a groove in the wheel structure by such mechanical operations as cutting, pressing, shaping or casting.
Examples of such prior art multi-piece wheel rims with sealing members may be found in the following prior art U.S. Pat. Nos.: 1,991,594; 2,802,507; 2,810,419; 2,827,100; 2,871,905; 3,007,741; 3,118,485; 3,593,764; 3,865,170; 3,880,219; 3,885,615; 4,102,379; 4,106,543; 4,234,236; 4,253,514; 4,327,791; 4,372,365; 4,438,797; 4,466,670; and 4,481,997.
The above listed U.S. Strader Pat. Nos. 4,327,791 and 4,481,997, assigned to the assignee herein, disclose take-apart military vehicle wheels employing O-ring sealing and adapted to be equipped with a safety insert device disposed internally of a tire mounted on the rim for supporting the tire tread in a deflated condition to thereby provide a so-called "run-flat" wheel construction. The Strader '997 patent also discloses and claims an important safety feature useful in multi-piece wheel rim assemblies, whether considered alone or in combination with safety inserts of the above-described type, which overcomes a significant safety hazard if it is attempted to inflate a tire mounted thereon when the various wheel assembly components are improperly positioned or seated, or to disassemble the rim when the tire mounted thereon is inflated. In the Strader '997 patent wheel construction, the disc and inboard rim part are made as one piece, and the O-ring is captured between a shoulder, at the junction of the disc with the inboard rim part, and an up-turned flange at the inner edge of the outboard rim part. Safety vent means in the form of a groove or aperture in the disc-inboard rim piece is located on the outboard side of the seal when in assembled position. Such safety vent means is operative to prevent inflation of a tire mounted on a wheel assembly when the wheel assembly components are improperly positioned and/or to automatically vent the tire cavity to atmosphere prior to disconnection of the outboard rim part should disassembly be attempted when the tire mounted thereon is inflated.
Although the aforementioned Strader '997 patent safety wheel and run-flat wheel construction has been manufactured commercially and operates successfully for use on certain military vehicles, certain problems nevertheless remain, such as cost of manufacture, lack of design flexibility to accommodate different wheel offsets, the need for special spin forming manufacturing equipment, the presence of difficult-to-manufacture skip-welds in the O-ring seal area and the need in some applications for increasing the inflation valve turret/stem-to-brake clearance.
Accordingly, an object of the present invention is to provide an improved take-apart wheel rim assembly for tubeless pneumatic tires, including safety tire and wheel assemblies of the above-described type which provides a safety vent feature, which may be of the aforementioned Strader '997 patent take-apart wheel constructions, while at the same time overcoming the aforementioned problems present in such wheel constructions.